YUI is a free, open source JavaScript and CSS framework for building richly interactive web applications.

Get Started Start using YUI 3.5.1 in two easy steps.

Why YUI?

Fast

YUI's lightweight core and modular architecture make it scalable, fast, and robust. Built by frontend engineers at Yahoo!, YUI powers the most popular websites in the world.

Complete

YUI's intuitive and well-documented API takes you from basic DOM handling to building performant and maintainable applications on desktop browsers, mobile devices, and servers.

Industrial Strength

A thriving community, a carefully architected infrastructure, and a comprehensive suite of tools help you code like a pro, from simple web pages to complex web applications.

Free & Open

YUI is free for all uses and is developed in the open on GitHub. Core team members can always be found in the forums and the #yui IRC channel on Freenode. Pull requests welcome!

A Few Examples

YUI Theater Videos

  • 57:20
    YUI Open Hours: 3.5.0 Uploader

    In this YUI Open Hours session from May 10, 2012, YUI engineer Allen Rabinovich provides a guided tour of the latest version of the YUI Uploader component, released with 3.5.0.

  • 52:44
    YUI Open Hours: 3.5.0 DataTable rendering tricks

    DataTable developer Luke Smith talks about the rendering algorithm and demonstrates some of the ways to customize the table data with column configurations and formatters.

  • 1:02:59
    YUI Open Hours: Photos Near Me on the Server

    In this YUI Open Hours session from April 26, 2012, YUI engineer Eric Ferraiuolo provides a guided tour of the latest version of his Photos Near Me application, which uses shared YUI code and Handlebars templates on the server (in Node.js) and on the client to provide an optimal experience for users regardless of whether they have JavaScript enabled.

YouTube icon YUI Theater on YouTube

@yuilibrary on Twitter